Indayara Bertoldi Martins

Evaluation of throughput and protection in optically switched metropolitan network architectures

In this study, we investigate the performance of optical packet/burst switched (OPS/OBS) architectures connected as mesh and as ring topologies for future optical metropolitan networks. Network throughput and protection to link failure under uniform traffic distribution for all nodes are investigated to evaluate the sensitivity of OPS/OBSN performance. Our data are based on analytic results and computer simulations that include a comparison between various mesh and ring topologies. We also consider detailed traffic distributions over the network links and the impact caused by failure of more or less loaded links, thus providing a method to select links that require protection, which can be very useful in network planning.

Dynamic traffic analysis of metro-access optical packet switching networks having mesh topologies

We have investigated the performance of various optical packet switched network (OPSN) architectures comprising optical bufferless nodes and fully connected mesh topologies, under uniform traffic distribution, i.e., all nodes generate the same traffic. We demonstrate that increasing the number of nodes in OSPNs does not necessarily increase performance, or even capacity. By establishing an efficiency parameter based on average number of hops and effective network capacity, decision tables and graphs can be generated and utilized in network planning. Moreover, regular and quasi- regular optimized topologies lead to lower latency, higher throughput, and lightpaths with significantly better traffic distribution. The optical nodes have simple configuration and are totally compatible with WDM networks.

Contribution to future metropolitan access network planning considering link failures in photonic switched networks

Photonic switching for traffic optimization in Metropolitan Access Optical Networks using technologies of optical packet/burst switching (OPS/OBS) seems to be a future-proof solution considering high capacity and the highly variable traffic in these networks. Looking for this future, we propose a study based on the analyze of survivability of traffic unconsidering protection mechanism but considering mesh and ring efficient topologies with node architecture to OPS. The results are obtained through computer modeling and simulation. The main parameters analyzed are as follows: capacity, average number of hops, packet loss fraction, and link utilization for each topology. These parameters are adopted to evaluate the performance of each topology considering failures. Minimum electronic buffering is included at node ingress (client side) to avoid packet loss in the access to the optical layer: high throughput and low latency. It is also observed that optical buffering is not necessary for adequate network performance.

A study in photonic switched networks considering link failure and ingress buffering

In this paper we study the behavior of traffic in Metropolitan Access Optical Networks with technologies of optical packet/burst switching (OPS/OBS), using computer modeling and simulations. We analyze network performance and the impact of link failure when electronic buffering at ingress (client input) to optical network is implemented. Mesh and ring topologies are chosen and parameters packet loss fraction and average number of hops are adopted for performance metrics. The use of minimum electronic buffering at ingress is demonstrated to improve access to the optical layer, and necessary to keep the packet loss fraction low and throughput high with low latency. We also show that optical buffering is not necessary for adequate network performance.

Improved Method for Evaluation of Network Throughput and Protection in Future Optically Switched Metropolitan Networks

In this work we investigate the performance of optical packet/burst switched (OPS/OBS) architectures connected as mesh and as ring topologies, for future optical metropolitan networks. Network throughput and protection to link failure under uniform traffic distribution for all nodes is investigated in order to evaluate the sensitivity of OPS/OBSN performance. Our results are based on analysis of simulations and comparison between various mesh (Manhattan St. type) and ring topologies. We also consider the detailed traffic distributions over the network links and the impact caused by failure of more or less loaded links, thus providing a way to select links that require protection.

Routing and spectrum allocation in flexgrid optical networks using differential evolution optimization

Flexible optical network (FON) architectures are considered a very promising solution where spectrum resources are allocated within flexible frequency grids. Routing and spectrum allocation (RSA) in FON is known to be an NP-complete problem. So far, this problem has been optimally solved for small instances by the application of integer linear programming and has been sub-optimally solved for more realistic instances by heuristic strategies. In this paper, we introduce the application of differential evolution (DE) to the RSA problem in flexible optical networks. Comparative studies show that in many cases DE outperforms many other well-known evolutionary computational approaches. Furthermore, the method typically requires few control parameters. An illustrative example is presented showing the effectiveness and efficiency of the proposed algorithm. Different heuristics and the DE-RSA algorithm are compared. To the best of our knowledge, our work is the first application of a DE algorithm to the RSA problem.

Influence of topological connectivity for transport in optical networks with amplified photonic switches

The present work analyzes the performance of optical networks with architecture based on mesh topology and photonic switching. We describe the analytical calculus based on theory concepts to estimate the standard performance and results of computer simulation to validate our expectations. The main adopted parameters for this analysis are the packet loss fraction (PLF) and average number of hop (ANH). We observe that the combination of these elements leads to a consistent account of performance, in terms of network traffic and packet delivery for optical packet and burst switching (OPS/OBS) metropolitan networks. Results show that combination of highly connected mesh topologies having an ingress e-buffer present high efficiency and throughput, with very low packet loss and low-latency, ensuring fast data delivery to the final receiver.

Future-Proof Photonic Switched Optical Networks for Metropolitan Access

Photonic Switching for traffic optimization in Metropolitan Access Optical Networks using technologies of optical packet/burst switching (OPS/OBS) seems to be a future-proof solution considering high-capacity and the highly variable traffic in these networks. In this study we propose and analyze through computer modeling and simulations network performance of OPS/OBS distributed switching networks and the impact of link failure when electronic buffering at ingress (client input) to optical network is also included. Mesh and ring topologies are chosen as more suitable topologies and the parameters packet loss fraction and average number of hops are adopted for performance metrics. Minimum electronic buffering is included at node ingress (client side) to improve lossless access to the optical layer, yielding high throughput and low latency. It is further observed that optical buffering is not necessary for adequate network performance.

Evolution of dynamic routing wavelength code assignment in WDM/OCDM OBS network

This paper proposes and investigates the performance of a dynamic routing and wavelength code assignment (RWCA) algorithm using hybrid technology with wavelength and optical code division multiplexing (WDM/OCDM) for Optical Burst Switching (OBS) network. An OCDM-based multigranularity optical cross-connect (MG-OXC) is used to enable the better granularity in optical path (wavelength and code) switching than the wavelength-based path. The results show that Random-Random heuristic has a better performance when the burst blocking probability as a function of traffic load is studied. In addition, show that WDM/OCDM technology increase the capacity and scalability in the optical network.

Proposal and Evaluation of Photonic Switching Architectures for High-Capacity Optical Access Networks

Considering that optical packet/burst switching (OPS/OBS) are considered strong candidates for metropolitan networks in the near future, this work is a contribution evaluating the performance of some network models based on OPS/OBS mesh/ring architectures. We use both the conventional models of ring and mesh (Manhattan Street type), and slightly modified models implementing new structures, with cases of unidirectional and of bi-directional links. Our main goal here is to find through computer simulations the better architectures, in terms of (higher) capacity and (lower) latency. We choose the parameters average number of hops, total number of deflections and packet loss fraction as metrics for network performance. We observe that networks with best performance are the ones with largest number of different paths between nodes.